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The three-dimensional structure of Saturn's E ring
Hedman, M. M.; Burns, J. A.; Hamilton, D. P. +1 more
Saturn's diffuse E ring consists of many tiny (micron and sub-micron) grains of water ice distributed between the orbits of Mimas and Titan. Various gravitational and non-gravitational forces perturb these particles' orbits, causing the ring's local particle density to vary noticeably with distance from the planet, height above the ring-plane, hou…
Small-scale variability in Saturn’s lower ionosphere
Matcheva, Katia I.; Barrow, Daniel J.
We perform and present a wavelet analysis on all 31 Cassini electron density profiles published to date (Nagy, A.F. et al. [2006]. J. Geophys. Res. 111 (A6), CiteID A06310; Kliore, A.J. et al. [2009]. J. Geophys. Res. 114 (A4), CiteID A04315). We detect several discrete scales of variability present in the observations. Small-scale variability (S …
Energetic electron observations of Rhea’s magnetospheric interaction
Gurnett, D. A.; Persoon, A. M.; Krupp, N. +12 more
Saturn’s moon Rhea is thought to be a simple plasma absorber, however, energetic particle observations in its vicinity show a variety of unexpected and complex interaction features that do not conform with our current understanding about plasma absorbing interactions. Energetic electron data are especially interesting, as they contain a series of …
Sublimation-driven erosion on Hyperion: Topographic analysis and landform simulation model tests
Schenk, Paul M.; White, Oliver L.; Moore, Jeffrey M. +2 more
The unique appearance of Hyperion can be explained in part by the loss to space of ballistic ejecta during impact events, as was proposed by Thomas et al. (Thomas, P.C. et al. [2007a]. Icarus 190, 573-584). We conclude that such loss is a partial explanation, accounting for the lack of appreciable intercrater plains on a saturation-cratered surfac…
Characterizing Io’s Pele, Tvashtar and Pillan plumes: Lessons learned from Hubble
Spencer, John R.; Jessup, Kandis Lea
Hubble Space Telescope/Wide Field and Planetary Camera 2 (HST/WFPC2) images of Io obtained between 1995 and 2007 between 0.24 and 0.42 µm led to the detection of the Pele plume in reflected sunlight in 1995 and 1999; imaging of the Pele plume via absorption of jovian light in 1996 and 1999; detection of the Prometheus-type Pillan plume in re…
Saturn's F ring as seen by Cassini UVIS: Kinematics and statistics
Colwell, Joshua E.; Esposito, Larry W.; Sremčević, Miodrag +1 more
We present a new orbital model of Saturn's F ring core based on 93 occultations by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and the Voyager radio and stellar occultations. We demonstrate that the core, despite its intrinsic variability, is well-described as an inclined, freely precessing ellipse. We find that post-fit residuals with a r…
Illumination conditions at the Asteroid 4 Vesta: Implications for the presence of water ice
Stubbs, Timothy J.; Wang, Yongli
The mean illumination conditions and surface temperatures over one orbital period are calculated for the Asteroid 4 Vesta using a coarse digital elevation model produced from Hubble Space Telescope images. Even with the anticipated effects of finer-scale topography taken into account, it is unlikely that any significant permanently shadowed region…
Classification of F ring features observed in Cassini UVIS occultations
Esposito, Larry W.; Sremčević, Miodrag; Meinke, Bonnie K. +1 more
The Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn’s F ring since July 2004. This work nearly doubles the number of features reported by Esposito et al. (Esposito, L.W. et al. [2008]. Icarus 194, 278-289). As the number of statistically significant features has grown…
Adhesion and collisional release of particles in dense planetary rings
Schmidt, Jürgen; Spahn, Frank; Bodrova, Anna +1 more
We propose a simple theoretical model for aggregative and fragmentative collisions in Saturn’s dense rings. In this model the ring matter consists of a bimodal size distribution: large (meter sized) boulders and a population of smaller particles (tens of centimeters down to dust). The small particles can adhesively stick to the boulders and can be…
Thermospheric/mesospheric temperatures on Venus: Results from ground-based high-resolution spectroscopy of CO 2 in 1990/1991 and comparison to results from 2009 and between other techniques
Mahieux, Arnaud; Sonnabend, Guido; Sornig, Manuela +8 more
We report temperatures in Venus' upper mesosphere/lower thermosphere, deduced from reanalyzing very high resolution infrared spectroscopy of CO 2 emission lines acquired in 1990 and 1991. Kinetic temperatures at ∼110 km altitude (0.15 Pa) are derived from the Doppler width of fully-resolved single line profiles measured near 10.4 µ…